1. Field of the Invention
This invention relates to small computers and similar electronic devices of the type that has a base assembly and an upper or component assembly that is raised by a spring into operating position, providing operator access to computer devices such as printing, data storage and other devices mounted in the assembly.
2. Description of the Prior Art
The use of a spring to balance and raise an upper assembly into an open or operating position is known in the art in early versions of the IBM Aptiva S-series personal computer media console. This spring, used to lift the Direct Access Storage Device (DASD) drive housing to the operating position, rests on the console base and attaches to the upper assembly drive housing by way of the spring ends which are inserted into holes in the DASD bracket. This design is functional and reliable but is not easy to reassemble when the upper assembly must be removed for service or upgrade of the DASD. The spring becomes free from the console base once the spring ends are disengaged from the upper assembly DASD bracket which normally hold the spring in tension.
U.S. Pat. No. 5,240,319 teaches an upper body opening/closing mechanism for electronic equipment. The upper body is hinged to the lower body with a hinge pin 5 resting in U shaped groove 9. A coil spring 17 is slipped over the hinge pin 5 before assembly. The ends of the coil spring are formed outward to become tangent to the coil and to engage holes in fixture 13 and 19 mounted to the lower body 1 and upper body 3 respectively with screws. This patent suffers from the cost and difficulty of assembly and re-assembly similar to the prior art described above although the spring remains with the upper assembly rather than the base after disassembly.
U.S. Pat. 5,500,982 shows a hinge mechanism for connecting a body portion 1 to a display portion 3 in the form of an upper assembly of a portable electronic apparatus. The hinge contains a friction portion in the form of a presser spring 45 acting on an oval shaft so as to increase friction as the display is moved past the vertical and the moment arm of the center of gravity becomes longer. The hinge also has torsion bars 46 which appear to act as second hinge pins for the first 90 degrees of hinge travel.
U.S. Pat. No. 5,041,818 is directed to a lid for a computer or the like and a hinge shaft having a flat end portion 21 for engagement with the computer casing. A spring clutch 22 surrounds the hinge shaft with an interference fit. The spring has an end 29 fixed between the lid and a small cover for the mechanism. The other end 28 of the spring is formed to allow a small angle of rotation of the spring relative to the shaft. As the lid is being raised in a clockwise direction in FIG. 4B, arm 23 can fall back against the cover and slightly unwind the spring to release friction force on the shaft. When the lid is closed in the counter clockwise direction, arm 26 stays with the shaft through a small angle, allowing the spring to wind up and tighten on the shaft to control closing of the lid.